Melting of magnetization plateaus for kagome and square-kagome lattice antiferromagnets

TL;DR

This study explores how magnetization plateaus in kagome and square-kagome antiferromagnets melt asymmetrically with temperature, revealing differences in their thermal behavior at specific magnetization levels.

Contribution

It provides the first detailed analysis of temperature effects on magnetization plateaus in kagome and square-kagome lattices, highlighting asymmetric melting phenomena.

Findings

Asymmetric melting of magnetization plateaus observed.

Differences in behavior between kagome and square-kagome lattices at 1/3 saturation.

Minimal susceptibility bends towards lower fields with increasing temperature.

Abstract

Unconventional features of the magnetization curve at zero temperature such as plateaus or jumps are a hallmark of frustrated spin systems. Very little is known about their behavior at non-zero temperatures. Here we investigate the temperature dependence of the magnetization curve of the kagome lattice antiferromagnet in particular at 1/3 of the saturation magnetization for large lattice sizes of up to N=48 spins. We discuss the phenomenon of asymmetric melting and trace it back to a combined effect of unbalanced magnetization steps on either side of the investigated plateau as well as on the behavior of the density of states across the plateau. We compare our findings to the square-kagome lattice that behaves similarly at low temperatures at zero field, but as we will demonstrate differently at 1/3 of the saturation magnetization. Both systems possess a flat one-magnon band and therefore share with the class of flat-band systems the general property that the plateau that precedes the jump to saturation melts asymmetrically but now with a minimal susceptibility that bends towards lower fields with increasing temperature.